According to a recent study by the DSL Forum, at the end of the first
quarter 2003 there were 41.3 million DSL lines deployed worldwide. The
biggest growth spurt occurred in Asia. In the U.S., the latest round of
data released by the FCC on broadband infiltration shows a 55 percent
increase in the number of high-speed lines installed in 2002, with DSL and
cable growing at a similar rate. This move toward broadband is having an
impact on the way TV is being delivered.
The rollout of digital networking infrastructure coupled with
deregulation, is opening the door for telcos and operators to offer
converged "Triple Play" services comprising broadband telephony,
Internet access and TV (or video). TV over IP, as opposed to traditional
cable or broadcast and satellite TV, utilizes digital broadband networks
such as ADSL, VDSL, fiber, LMDS and wireless LANs to transmit programming
to consumers' homes. Telcos are delivering TV over their IP networks for
regular TV services, time-shifted TV or personal video recorder (PVR)
services, Interactive TV and TV to the desktop. This last application is
one of the hallmarks of TV over IP versatility. Viewers can watch TV on
their PCs or on their TVs.
Telcos and operators have had no choice but to tread the IP road.
Deregulation has increased competition in their traditional telephony
markets. The threat is not only coming from the cable companies, but also
from mobile services, which have reduced the number of land-based phone
lines that many households need. Likewise, the growing prevalence of
broadband Internet access is making a second dial-up line unnecessary in
many homes. Telcos are adopting TV over IP strategies as a pro-active
stance, before cable companies start infringing on their traditional
revenue channels, and also as a way of justifying DSL offerings. Based on
this approach, for some telcos it is not financially viable to offer plain
broadband intended for Internet use, without the additional TV over IP
service. By streaming TV over their native infrastructures, telcos have a
chance to recoup or gain market share and increase revenues by offering a
wider range of services.
With TV over IP, operators can offer a greater level of service to
their customers. The fact that customers receive converged services on a
single pipe and interface with a single provider for all communication
needs results in easier technical maintenance, streamlined billing and
improved customer service. In this regard, many telcos are in a good
position to capitalize on the high level of existing service that they
offer their customers. What's more, by utilizing digital networks, telcos
and operators can offer far more sophisticated programming packages. It is
possible to target specific channels at small groups of viewers, based on
pre-defined viewing profiles.
GETTING TV OVER PHONE LINES: DSL APPLICATION ARCHITECTURE
Streaming TV over DSL lines is possible by using high quality MPEG video.
The various MPEG standards allow application developers to create
customized trade-offs between playback rate, quality, bandwidth and cost.
MPEG-1, MPEG-2 and MPEG-4 offer different compression rates and
schemes, allowing service providers to offer various video streaming
services:
- MPEG-1 provides very good quality at playback rates of up to three
Mbps;
- MPEG-2 provides a compression solution for applications that are not
limited by bandwidths (three to 15 Mbps). Such a broad compression
range means that it is not necessary to sacrifice quality to
compression rate limitations; and
- MPEG-4 is a set of compression/decompression formats and streaming
technologies that address the need for distributing rich interactive
media over narrow and broadband networks. Although MPEG-4 covers more
or less the same encoding range as MPEG-1 and MPEG-2, its target
applications are different. MPEG-4 defines interactivity, scalability
and streaming of rich media. Content compressed according to the
MPEG-4 standard can be streamed over the broad or narrowband Internet,
used in Interactive TV applications or streamed to wireless appliances
such as cellular phones and PDAs (Personal Digital Assistants).
DSL is well suited for TV over IP. It provides sufficient bandwidth and
bi-directional communication for management applications, such as billing
and interactivity. DSL incorporates forward error correction that
dramatically reduces errors caused by impulse noise. Most important: Since
DSL modems are installed on existing copper lines, there is no need for
massive re-wiring. Thus, the cost of initial deployment is financially
feasible.
ADSL
ADSL can support last-mile bandwidths between 512 Kbps and 8 Mbps. The
actual bandwidth available depends on the distance between the end point
and the ADSL DSLAM. Depending on the last mile bandwidth available, users
can receive two channels of video. In this case, two IP STBs
(Set-Top-Boxes) will reside at the end point (one STB for each channel).
An important part of the central office configuration is making sure
that the ADSL DSLAM supports multicast. If it doesn't, then the level III
device has to replicate all streams for each channel requested. This is
liable to cause congestion at the DSLAM. For example, if the DSLAM at the
central office services 20 end points and all end points request channel
three, then the level III device has to feed channel three into the DSLAM
20 times. If on the other hand the DSLAM supports multicast, it would
receive one stream of channel three and replicate it for each end point.
VDSL
VDSL is an optimal network infrastructure for TV over IP services. VDSL
configuration rests on fiber connectivity over the backbone at bit rates
of 155 Mbps and up. Transmission from the last mile network node to the
end point is at bit rates of between 10 and 40 Mbps. The high bandwidths
supported by VDSL enable consumers to receive multiple channels for
playback on multiple TV sets. With VDSL, the backbone infrastructure is
based on fiber to the curb/basement while the last mile solution uses VDSL
over the copper telephone line.
FIBER TO THE HOME (FTTH)
Another very suitable infrastructure is Fiber to the Home (FTTH). FTTH
configuration rests on fiber connectivity from the video IP head-end to
the end point. In this configuration, video is transmitted over a fiber
backbone at more than 155 Mbps. Last mile configuration consists of a
100Base-T network. Such wide bandwidths allow users to receive multiple
channels, which are played back by IP set-top boxes.
Nuts and Bolts
When implemented by a telco or operator, a TV over IP solution would
typically stream between 50 and 150 TV channels over an IP network.
Content is streamed from the operator's IP head-end over the backbone to a
central/regional office. At the central office, the video is distributed
over the "last mile" to the consumer's home. Complimentary
streaming equipment at the central office allows operators to insert
additional channels of local content, which can be targeted at specific
areas or groups of users. At the consumer's home, an IP set-top box
displays the video stream on a TV set.
Transparent Delivery
At the end of the day, people in their living rooms don't really care what
type of network delivers their favorite show. What they do care about is
quality and added value services. This is where TV over IP can influence
consumers' levels of expectations. Telcos or operators that offer
"triple play" services comprising of telephony, high-speed
Internet, and advanced digital TV services can provide real added value to
their customers.
Danna Bethlehem is publications and online marketing manager for
Optibase, Ltd. Optibase is a pioneer and market leader in broadband media
gateways and MPEG-1 and MPEG-2 encoding and streaming platforms. Propelled
by sophisticated technology and market expertise, Optibase's products are
at the core of professional digital video solutions worldwide. Optibase's
products enable applications such as TV entertainment over IP networks,
digital video archiving, distance learning and business television. They
also serve the professional video market for high-end content creation
applications. Optibase products are marketed in over 40 countries through
a combination of direct sales, independent distributors, system
integrators and OEM partners. For more information, please visit www.optibase.com. |
